Bad silicone - A sad day

[Phoenixmsb]

What a sad day - installed with clear silicone and rivets, (3) interior panels last week. More time in the garage last night to install more and I found all the silicone that I put on the panels before riveting was still a liquid mess - it never got solid! So, un-rivet all the panels, clean off the goopy mess then I found I'm out of rivets.

Ordered more last night so roadster is on hold for a week waiting on rivets.

Was using Dap Silicone from Home Depot but now have switched to GE Black Silicone. Hope it was just a bad batch but I'm not taking any chances by trying that brand again.

[toadster]

i've heard good reviews of Bostik 1100FS (sold at Breeze Automotive) https://www.breezeautomotive.com/shop/bostik-1100-urethane-adhesive-sealant-black/

or Sikaflex-221 ($12 with free Amazon Prime shipping) (https://amzn.to/2Tvb77n)

[initiator]

I've heard of problems when the silicone gets too old. I use the GE Silicone II clear and it's been flawless for me. I do check the manufacturing date on the tubes when I buy them, though.

[rich grsc]

I'll bet it was old, and out of date, had the same thing happen to me years ago. There is no need to spend $12 on special sealant, I've use GE II silicone on three builds, and it has NEVER failed. Fact is, after it's cured it's hard to get panels apart.

[Logan]

Any consideration for panel adhesive that is silicone-free? Something like polyurethane?

Silicone is bad for paint jobs among other things car related.

[Jeff Kleiner]

Like Rich I have always used GE Silicone II. A whole bunch of cars over the course of 13 years and no issues ever. I'm kind of cheap and tend to follow the K.I.S.S. school of thought but if you prefer the "It costs more so it must be better" philosophy go ahead and spend away :)

Jeff

[KDubU]

Yup GE silicone II works. Sorry about the having to redo.

[Papa]

I used the GE Silicone II as well.

[michael everson]

Is GE Silicone II twice as good as Silicone I?
Asking for a friend.
Mike

[Papa]

Is GE Silicone II twice as good as Silicone I?
Asking for a friend.
Mike

That would be three times as good if you understand my signature. :p

[cv2065]

GE Silicone II Black for me

[BEAR-AvHistory]

GE II clear from Home Depot.

[Phoenixmsb]

Thank you everyone for the advice. An hour of cleaning the old stuff off then I picked up GE Silicone II Black today. I'll be joining you all on the road someday soon I hope!

Thanks again!

[CDXXVII]

i've heard good reviews of Bostik 1100FS (sold at Breeze Automotive) https://www.breezeautomotive.com/shop/bostik-1100-urethane-adhesive-sealant-black/

or Sikaflex-221 ($12 with free Amazon Prime shipping) (https://amzn.to/2Tvb77n)

Bostik 1100FS is all I used on my build. Works great but be aware of it's shelf life. I believe you get about 6 months. After that it starts hardening in the tube even if unused and sealed. Ask me how I know!!

[bobl]

That would be three times as good if you understand my signature. :p

Hey Papa, I understand your signature line. Back in the infancy of computers I wrote many a line of binary code. Now I do good to even turn on a computer, but I do understand how it works...Back on topic, I use GE Silicone II

Bob

[edwardb]

To pile on here, I've also used GE Silicone II from HD on several builds. After reading a number of posts, decided to give Sikaflex-221 a try on my Coupe. Works OK I guess, but (1) more expensive, (2) harder to clean up, (3) don't see the advantage. I too have had to take panels apart after using the GE, and it's hard to do without ruining something. In the future will go back to the GE stuff. Agreed silicone isn't a friend of paint. But typically the body isn't around when using it to apply the panels. And you'll want to keep things neat and not smear it all over yourself and your work anyway. Really no reason there should be any contamination from it. I've heard several express concerns. Have not heard about anyone who actually had any issues, including on the ones I've done.

[GFX2043mtu]

Sikaflex 221 is great stuff if you know how and when to use it. The bonding strength is vastly higher then the normal GE silicone that you can pull off once cured. If you use it between panels or between panels and the chassis it will make them very difficult to impossible to remove with out damage once it’s cures. I spec it out all the time on Locomotive cooling systems as it is highly effective to seal parts against water and has a very long service life. One tip is once applied you can spray it with soapy and then work it as it won’t stick to what is wet and is very workable when creating seams. Personally I used GE silicone between the chassis and aluminum panels and a modified polyurethane adheasive on the panel joints to seal them. I also used the polyurethane in the drivers foot box to bond the transmission tunnel panel to the round tube on the drivers side. This is because it has a very high bonding strength and is very stiff as to lock the panel to the tube. It’s all personal preference just know the pros and cons of what your using.

[edwardb]

Sikaflex 221 is great stuff if you know how and when to use it. The bonding strength is vastly higher then the normal GE silicone that you can pull off once cured. If you use it between panels or between panels and the chassis it will make them very difficult to impossible to remove with out damage once it’s cures. I spec it out all the time on Locomotive cooling systems as it is highly effective to seal parts against water and has a very long service life. One tip is once applied you can spray it with soapy and then work it as it won’t stick to what is wet and is very workable when creating seams. Personally I used GE silicone between the chassis and aluminum panels and a modified polyurethane adheasive on the panel joints to seal them. I also used the polyurethane in the drivers foot box to bond the transmission tunnel panel to the round tube on the drivers side. This is because it has a very high bonding strength and is very stiff as to lock the panel to the tube. It’s all personal preference just know the pros and cons of what your using.

All good points and no question the Sikaflex 221 has a higher bond strength than GE silicone. Which is, after all, mainly intended to be a sealer not a bonder. The question in my mind is whether it's needed. Adhesive strength doesn't matter too much if it's stronger than the underlying material. Which I've found when taking parts apart when GE silicone was used. Once the rivets are drilled out, it's nearly impossible to remove the aluminum without deforming to the point of not being usable.

I see two topics come up with new builders all the time. (1) Concern about heat through the panels, and (what I consider) extreme measures to deal with it. Another subject for another thread. And (2) Concern the panels will "rattle" or come apart if not properly secured. This leads to discussions about how many rivets, what adhesive, etc. First I don't think new builders realize just how stiff the chassis is. Anything reasonably attached is not going to rattle. Whenever I take people for rides, they are surprised and comment about how stiff and solid the chassis is, and the total absence of squeaks or rattles. Point being that if the panels are installed per the instructions, with rivets every two inches between panels and every three inches into the frame, and silicone RTV type adhesive, nothing is going to come apart or rattle. Ever. Going to a higher end adhesive certainly doesn't hurt anything. But in this case, just not convinced it adds anything.

[RBachman]

i've heard good reviews of Bostik 1100FS (sold at Breeze Automotive) https://www.breezeautomotive.com/shop/bostik-1100-urethane-adhesive-sealant-black/

or Sikaflex-221 ($12 with free Amazon Prime shipping) (https://amzn.to/2Tvb77n)

Dittos on the Breeze's Bostic 1100FS. Stuff is great!